Is java Date/Calendar a bug?

[Li Shangqiang]

I used java.util.Calendar like this:
Calendar calendar = new GregorianCalendar(2001, 6, 30);
calendar.add(Calendar.DATE, 1);
//or calendar.add(Calendar.DATE, 1);
//or calendar.add(Calendar.HOUR, 24);
System.out.println("year: "+calendar.get(Calendar.YEAR)+
"\n month: "+calendar.get(Calendar.MONTH)+
"\n day: "+calendar.get(Calendar.DAY_OF_MONTH)+
"\n hour: "+calendar.get(Calendar.HOUR)+
"\n minute: "+calendar.get(Calendar.MINUTE)+
"\n sencond: "+calendar.get(Calendar.SECOND)
);
the result is always 2001-6-31!
then i use java.util.Date:
Date date = new Date(2001, 6, 30);
long current = date.getTime();
current += 24 * 3600 * 1000; //add one day
System.out.println(..
and the result is the same!
who answer me?

[rani bedi]

There is no problem with the java.util.date object.
If you try to convert the time back into the date object you would see that it prints the next date.

Date date = new Date(2001, 6, 30);
long current = date.getTime();
current += 24 * 3600 * 1000; //add one day
Date newDate = new Date(current);
System.out.println(" date " + date);
System.out.println(" newDate " + newDate);

[Paul Stevens]

If you are referring to 6-31 and thinking it is June 31 you are mistaken. Java months start at 0 for Jan. So 6-31 is Jul 31.

[Li Shangqiang]

Yes, that's the problem.
I'v got it.